Too few people are comfortable with jokes at funerals. We had clowns at my mother's (who was a clown), and with the exception of immediate family and people she knew from clowning, people were really uncomfortable with that.
Clowns at a funeral sounds wonderful. A good friend of mine went to clown college. It's weird... as devoutly religious as I am... my funeral won't be at a church. It'll be a party. Recently I've considered being cremated and having my ashes packed into a decent fireworks display. I'll need to consult some pyro-pro's to see if this is feasible. Picture it - a massive BBQ - balloons for the kids, ice cold coke out of the bottle, music blaring, and then BOOM - fireworks. The least I can do when I kick the final can is give my buddies a decent party.